The widely used measurement of a urinary flow rate is the simplest investigation in the assessment of voiding dysfunction. The urinary flow rate provides important and useful information about whether a problem exists in a patient's lower urinary tract. Additionally, the measurement of urinary flow rate may indicate the degree and possible etiology of an ongoing bladder pathology.
A uroflowmeter is a well-known device for measuring the rate of urine flow. Uroflowmeters that are commonly used today operate using one of three well-known methods: (1) a rotating disk method, (2) an electronic dipstick method, or (3) a gravimetric method. With the rotating disk method, voided fluid is directed onto a rotating disk and the amount landing on the disk produces a proportionate increase in its inertia. The power required to keep the disk rotating at a constant rate is measured, allowing calculation of the flow rate of fluid. In the electronic dipstick method, a dipstick is mounted in a collecting chamber and as urine accumulates the electrical capacitance of the dipstick changes, allowing calculation of the rate of fluid accumulation and hence the flow rate. With the gravimetric method, the weight of collected fluid or the hydrostatic pressure at the base of collecting cylinder is measured.
Standard uroflowmetry is performed at specified procedure areas by having a person urinate into a special funnel that is connected to a measuring instrument. Normally, standard uroflowmetry is performed on an outpatient basis at urology clinics or as part of patient stay in the hospital. Commercially available uroflowmeters require maintenance, are large in size and the procedure itself takes a lot of clinic time. Importantly, the voiding process is somewhat unnatural and the patient's privacy and comfort are limited. Furthermore, the use of uroflowmeters in hospitals and doctor's offices poses a risk to medical personnel of contacting urine excrements. Additionally, collecting data using today's commercially available portable uroflowmeters is still impractical because they are available only to a limited number of patients producing only limited number of measurements.
Hand-held computers and pen-and-pencil voiding diaries have been used to collect information regarding urination events including volume, frequency and urgency of urination. The sound of urination is apparently not collected with such computers, and the data are not recorded automatically, but rather are elicited via answers to specific questions.
The sound of urine flow through the urethra has been recorded in electronic format and analyzed to develop a graphic depiction of characteristics of the urination in patients with urethral narrowing due to stricture. It is believed that no prediction of lower urinary tract function has been made using such sound information, alone or with data regarding the urgency of urination.
For these reasons, a need exists for improved systems for and methods of assessing lower urinary tract function and symptoms associated with dysfunction in a manner that is convenient and easy to use in a non-stressful and risk-free environment by persons with limited training.